JPH0454161B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for measuring valve play between an intake valve and an exhaust valve of a piston engine.

The reason why it is important for piston engines to have accurate adjustment of the valve play is that the wear and tear on the valve drive section is largely affected by this play, and the wear and tear on the valve drive section is This is because, if it exceeds a certain permissible limit, it will cause engine malfunction, decrease in output, etc.

Generally, the free play of the valve is determined manually using a type of gauge, i.e. several thin tinplate plates of different thicknesses, which are connected to the disc-shaped base of the cam and the working surface of the dish-shaped tappet. or between other appropriate members. The play of the valve is then determined from the thickness of the tin plate which can still be inserted or which can no longer be inserted. However, this test, of course, requires the engine to be stopped and the valve drive to be accessible beforehand, and therefore this manual method does not introduce stress or individual pressure while the engine is running. In addition to the disadvantage that it may not be possible to measure the free play of the valve, which usually fluctuates under the influence of the movement of the parts of the Another drawback is that it is inconvenient to regularly inspect a piston engine that is in use.

In addition, as shown in Japanese Patent Publication No. 61-8251, the level of noise generated by detecting the mechanical vibrations generated when each intake valve and exhaust valve collide with the rocker arm or valve seat during piston engine operation is There is a method of measuring whether the valve adjustment is good or bad, including the valve play. However, since this method detects the piston engine by actually operating it, it is difficult to avoid the effects of noise, vibration, etc. caused by combustion, etc., and it has the disadvantage that it cannot be easily measured.

The present invention has been developed in view of the above circumstances, and it is possible to easily and quickly measure the actual free play of each valve while eliminating the effects associated with combustion in a piston engine, and to obtain reliable data. Disassemble the installed piston engine and
To provide a play measuring device for an intake valve and an exhaust valve, which avoids reassembly work as much as possible.

This invention claims that the metallic noise when opening and closing the valve deviates from the theoretical valve opening and closing point known from the crankshaft operating curve or cam operating curve, that is, it deviates by a time that is directly related to the free play of the valve. This was done based on consideration, especially when the valve is opened, the strength of the metallic noise mentioned above is mainly determined by the final collision speed between the two members of the valve drive part that have a play margin. This was done based on the consideration that the intensity of the noise when the valve closes is mainly determined by the final collision speed between the valve head and the valve seat. Based on this consideration, the present invention has the following structure, that is, a piston engine is driven from the outside for measuring valve play, and the surface of the valve drive part of this piston engine is subjected to vibrations caused by solid-borne sound. At least one vibration sensor for detecting
the vibration sensor is connected to an evaluation circuit, and is configured to send vibrations caused by solid-borne sound occurring at the location where the vibration sensor is installed to the evaluation circuit; and the crank mechanism of the piston engine. An angular transmitter is arranged at, the transmitter being connected to the evaluation circuit and configured to cooperate therewith to generate a reference signal in response to at least one predetermined angular position of the crank mechanism. provided that the above-mentioned evaluation circuit comprises a gate circuit, which gate circuit is energized by the reference signal of the angle transmitter, and that the above-mentioned evaluation circuit comprises a gate circuit, which gate circuit is energized by the reference signal of the angle transmitter, and that the crank configured to be open to signals due to structure-borne sound for a period known from the angle diagram, and the signal passing through the gate circuit is sent to a boundary value circuit connected to said evaluation circuit; This boundary value circuit has two thresholds for each monitoring period of the gate circuit, one threshold being higher than the background signal level in the absence of valve noise, and the other threshold being for each individual valve. The boundary value circuit is set higher than the maximum signal caused by the boundary value, and is configured to display the pass/fail judgment results obtained by comparison with these threshold values on a display device connected to the boundary value circuit. We have created a valve play measuring device with a structure consisting of the following.

According to a valve actuation test device for a piston engine disclosed in European Patent Application No. 31806, microphones are attached to the outside of the intake pipe and exhaust pipe of a piston engine driven from the outside for the purpose of this test. The signal sent from this microphone, mainly due to the frictional noise generated by the non-tight valve, is sent to a gate circuit controlled by the crank angle of this piston engine. In this known device, airborne sound is advantageously used for the purpose of checking the airtightness of a valve, but on the other hand, the signal generated due to airborne sound remains for a relatively long time, for example at the time of signal processing. Since the valve is connected even to the ground, it is impossible to obtain any measure of the valve's free play. Although it is possible to check the actual operating timing of the valves using this known device, it is necessary to remove the intake and exhaust pipes for each valve, and to connect the microphone to the opening of the cylinder head via a fairly expensive adapter. Must be installed.

On the other hand, according to the structure of the present invention described above, a signal based on solid-borne sound can be extracted using a solid-borne sound sensor without any special assembly or reassembly work for the piston engine. Also, since the intensity of solid-borne sound depends only on the impact between the valve and the tappet, it can be measured accurately without being influenced by surrounding great-grandchildren. In addition, this signal has a short duration, making it suitable for measurements that deal with very short time intervals, such as those caused by valve play. In addition, since the piston engine is driven not by combustion but by an external motor etc. under conditions such as the rotation speed suitable for measurement, it is difficult to set constant conditions, and temperature changes and noise accompanying combustion occur. Fluctuation factors can be eliminated, and valve play can be accurately measured using a simpler device. The monitoring period for the gate circuit is set such that the time point at which the period is determined from the crankshaft angle curve or the cam angle curve, taking into account the theoretical play of the valve, coincides with the starting point of the gate circuit opening timing. This is done because the noise generated at this point directly corresponds to the opening of the gate circuit and therefore a relatively strong signal can be recorded.

Valve play can be sufficiently measured or controlled simply by examining the noise at one of the two dead centers of valve movement, that is, when the valve opens or closes, but the reason for this is that if the valve play is slightly adjusted. This is because the effect always appears in the same way both when the valve is open and when the valve is closed. However, if the method of the present invention is used to check both dead centers of valve movement, it is advantageous for improving measurement accuracy or preventing measurement errors.

In another embodiment of the invention, the boundary value circuit has two
One threshold is set higher than the background signal level in the absence of valve noise, and the other threshold is set higher than the maximum signal due to an individual valve. This allows us to test whether or not a signal higher than the background noise is generated in the crankshaft angle range where some noise is expected to occur even if the valve play is adjusted correctly, and The test can be performed separately to determine whether a signal exceeding the maximum noise signal of each valve is output in the angular range. If the result of the first test is "fail", it means that the play adjustment of the valve is incorrect, that is, the timing of the noise generation when opening and closing the valve is either too early or too late. If the result of the second test is not ``no,'' one or at least one valve other than that valve is
This indicates that the noise from two other valves is occurring at the same time, that is, the valve play adjustment is also incorrect. Thus, when the valve play of the entire piston engine is correctly adjusted, the above-mentioned first
The result of the test is not "fail", and the result of the second test should be "fail".

In a further advantageous embodiment, a rectifier circuit and an adder connected thereto are connected before the boundary value circuit, so that the strength of the signal added for comparison with the threshold value is increased; The accuracy of this device is improved.

In a further advantageous embodiment, a plurality of opening periods of the gate circuit activated by the reference signal from the angle transmitter are determined not only by their relative temporal positions but also by their individual lengths. Since it is configured so that it can be adjusted at the circuit, it is particularly advantageous if the height of the threshold value for each monitoring period of the gate circuit can be adjusted individually. Thereby, the device of the present invention can be adapted to various types of piston engines to be tested in which the temporal operating states of the valve drive portions are different.

The embodiment shown in the figure will be described below.

A four-cylinder internal combustion engine 1 shown in FIG. 1 is driven externally by a motor 2 via a coupling shaft 3 for the purpose of testing valve play (or clearance). Vibration sensors 5 are provided at two predetermined locations in the region of the valve drive unit 4, and the sensors 5 are for detecting vibrations on the surface of the engine 1 caused by sound propagating through solid objects. All of them are connected to an evaluation circuit via a conductor 6, and a signal corresponding to solid-borne sound generated at the location where the sensor 5 is installed is inputted to the evaluation circuit from the sensor 5. . The position of the vibration sensor 5 in the figure is merely an example, and it is of course possible to change it freely depending on the situation. Depending on the situation, a single vibration sensor or two or more vibration sensors may be used. It's okay.

An angle transmitter 8 is provided at the flywheel 7 of the internal combustion engine 1, which transmitter 8 is connected to the above-mentioned evaluation circuit and cooperates with it to determine at least one specific angular position of the engine crankshaft. generates a reference signal corresponding to

The gate circuit 9 included in the above evaluation circuit is
energized by receiving a reference signal from the angle transmitter 8;
At least at a point known from the crank angle diagram, i.e. at one of the two dead centers for each stroke of the valve, it is open to the signal due to structure-borne sound input from the conductor 6, i.e. it passes this signal. be able to. In this way, the relative timing relationship and length of the open period of the gate circuit 9 excited by the reference signal from the angle transmitter 8 can be adjusted by the adjustment device 10.

The signal from the vibration sensor 5 that has passed through the gate circuit 9 is sent to the limit value circuit 13 via the rectifier circuit 11 and the adder 12 in the example shown in the figure.
The signal is compared with two reference level values, ie, threshold values, and the result is displayed on a display device 14 connected to the circuit 13. Limit value circuit 13
Regarding the threshold value given to , the height can be adjusted by the adjustment device 15 for each monitoring period of the gate circuit 9.

It should be noted here that the functions described below can be provided to individual components in any manner, and such circuits are known in the art, and that the present invention In view of the purpose of the above, it does not matter whether such a circuit or a group of circuits is constructed in hardware or software.

To simplify the explanation, internal combustion engine 1-4 in FIG.
The operation of the device according to the invention will now be explained in more detail with reference to the diagrams of FIGS. 2 to 5, in which only one of the cylinders is shown.

Figure 2 shows the stroke curve of the piston in a four-stroke engine in the area sandwiched between two ignition top dead centers 16, that is, one complete cycle. The interval includes two bottom dead centers 17 and one intake/exhaust switching top dead center 18. Correspondingly, in FIG. 3, the stroke curves of the cams for operating the valves are indicated by reference numeral 19 for the exhaust valve and reference numeral 2 for the intake valve.
Each is shown as 0.

Due to the play S (see Fig. 3) that occurs during valve drive, the actual opening timing 21 of the exhaust valve and opening timing 22 of the intake valve are somewhat delayed from the timing when the corresponding cams start rising. Conversely, the actual exhaust valve closing timing 23 and intake valve closing timing 24 are somewhat earlier than the corresponding cam lifting stop timings. Therefore, when the valve for intake and exhaust starts operating, a certain degree of relative movement or relative speed is generated between the parts having the above-mentioned play S, while on the other hand, when the intake and exhaust are completed, that is, the valve head is Relative velocities also occur between the parts when they abut the valve seat, which leads to collisions between the corresponding metal parts and a consequent perceptible noise. These noises correspond to Figure 3,
For example, a detectable signal accompanying solid-borne sound detected by the vibration sensor 5 in FIG. 1 is generated as shown in FIG. 4.

For example, the signal from the vibration sensor 5 generated during the above-mentioned open period is guided to the rectifier circuit 11 through a gate circuit 9 that cooperates with the angle transmitter 8 based on a signal train as shown in FIG. The latter signals are added in the adder 12 during the corresponding monitoring period, ie the opening period of the gate circuit. After the end of this monitoring period, the accumulated signal present in the adder 12 after a settable fixed time is converted to 2 in the limit value circuit 13.
The lower and smaller of these thresholds is higher than the background reference value that would exist in the absence of noise associated with valve operation, and the upper threshold is simply It is set higher than the maximum signal value caused by one valve. Thus, the limit value circuit 13 provides two output signals exceeding these threshold values on the display device 14, and these output signals can be used as output values for determining whether the valve has free play or not.

Unlike the illustrated embodiment, the above detection, check, etc. may be performed only for one of the two dead centers, that is, either the dead center when the valve is open or the dead center when the valve is closed. The reason for this is that, as clearly shown in FIG. 3, the cam angle with respect to the valve play S changes over time in the same manner when the valve is open and when the valve is closed. No matter which of the testing methods described above is used, it is possible to obtain an accurate and error-free output signal regarding the free play of the valve at both dead centers during valve operation.

As is clear from the above, if the valve play S deviates from the target value previously determined by the position of the monitoring period given to the gate circuit 9 (see Figure 5), that is, the valve play If the play S is too large or too small, a comparison with a predetermined threshold in the limit value circuit 13 directly yields a significant signal, which indicates that the actually existing valve play S is acceptable. It directly provides a criterion for determining whether or not it is true.

If no suitable signal is obtained within the monitoring period indicating the play of a precisely adjusted valve, as a measure within the scope of the present invention, this monitoring period may be changed in time to In other words, it is also possible to make a small displacement with respect to the crank angle and thereby obtain an output signal indicating whether the valve has too little or too much free play. This could be carried out, for example, by means of the regulating device 10, if desired.

By equipping the above-mentioned display device with a memory for accumulating the data obtained by comparison with the threshold value within the individual monitoring periods, a comprehensive analysis of the valve actuation can be carried out, for example in the case of a crank mechanism. The data after multiple cycles can be output in the form of an average of the data for each single cycle, which in turn improves the accuracy of measurement.

[Brief explanation of the drawing]

The figures show the device of the present invention; Fig. 1 is its block diagram, Fig. 2 is the piston operating curve of the internal combustion engine in Fig. 1, Fig. 3 is the cam operating curve, and Fig. 4 is the solid-borne sound Time chart of the signal shown, No. 5
The figure is a time chart showing signals for controlling the gate circuit in the evaluation circuit in FIG. 1. DESCRIPTION OF SYMBOLS 1... Internal combustion engine, 4... Valve drive part, 5... Vibration sensor, 8... Angle transmitter, 9... Gate circuit,
11... Rectifier circuit, 12... Adder, 13... Limit value circuit, 14... Display device.

Claims (1)

[Scope of Claims] 1. A device for measuring the valve play between an intake valve and an exhaust valve of a piston engine, wherein the piston engine 1 is driven from the outside for this measurement; and the valve drive of the piston engine 1. At least one vibration sensor 5 for detecting vibrations caused by solid-borne sound is arranged on the surface of the section 4, and this vibration sensor 5 is connected to an evaluation circuit and detects vibrations generated at the location where the vibration sensor 5 is arranged. The angle transmitter 8 is connected to the crank mechanism of the piston engine 1.
is arranged, and the transmitter 8 is connected to the above-mentioned evaluation circuit and configured to co-operate therewith to generate a reference signal in response to at least one predetermined angular position of the crank mechanism. The above evaluation circuit comprises a gate circuit 9, which is energized by the reference signal of the angle transmitter 8, and which is energized by the reference signal of the angle transmitter 8, and the crank circuit 9 is activated with respect to at least one of the two dead centers associated with each stroke of the valve. It is configured to be open to signals due to structure-borne sound for a period known from the angle diagram, and that the signals passing through the gate circuit 9 are sent to a boundary value circuit 13 connected to the evaluation circuit. The boundary value circuit 13 has two threshold values for each monitoring period of the gate circuit 9, one of which is higher than the background signal level when there is no valve noise, and the other of which is higher than the background signal level when there is no valve noise. The display device 1 connected to the boundary value circuit 13 displays the pass/fail judgment results obtained by comparison with these threshold values, which are set higher than the maximum signal caused by each individual valve.
4. A valve play measuring device characterized by the following: 2. A rectifier circuit 11 is installed before the boundary value circuit 13.
2. The device according to claim 1, further comprising an adder 12 connected thereto. 3. The plurality of opening periods of the gate circuit 9 activated by the reference signal from the angle transmitter 8 are configured such that their relative temporal positions as well as their individual lengths can be adjusted in the evaluation circuit. Apparatus according to claim 1 or 2. 4. The device according to claim 2 or 3, wherein the height of the threshold value of each monitoring period of the gate circuit 9 can be adjusted individually.